This invention relates to regulating devices for rotary drives of winders wherein the material to be unwound is to be transferred with a high degree of constancy of velocity and a high degree of constancy of tension to another device. The winders of weaving machines are a prominent example where such regulating devices are needed. In that instance the movements of the dancer of the weaving device are used as the regulating quantity.
In weaving machines the warp threads should be supplied from the winder of the machines with as constant velocity and as constant tension as possible. In weaving the angular relation of the threads of the warp results in pulsating movements of its speed or velocity, and consequently the so-called dancer is also subject to small movements. The acceleration of the movements of the dancer decreases, as the constancy of the threads supplied by the warp beam increases. The more the evenness of the tension of the warp threads supplied by the warp beam increases, the smaller the movements of the dancer, and the smaller the mass of the dancer, so that the accelerating forces also remain small. This is the reason why dancers involving a large mass have not been used as a means for regulating the tension of the threads, or filaments. There is a trend toward minimizing the mass of the dancer, and to use the dancer as a storage means to regulate the rpms of the warp beam by a so-called "Two point control". In such a kind of control only the uppermost and the lowermost excursions or amplitudes of the dancer are used, but the smaller excursions of the dancer remain unused in the process of regulation. In other words, only the uppermost and the lowermost dead centers of the stroke of the dancer can be used for regulating purposes. This results in that the drive for the warp beam receives in the "Two point control" method only "on" or "off" commands. This results in that the warp beam of weaving machines having " Two point regulators" are always supplied with "on" or "off" commands, so that the supply of the warp filaments becomes too irregular and that their tension are subject to regular but unavoidable changes or variations.
The prior art Swiss Pat. No. 611,951 discloses means for maintaining continually constant the tension of the unwinding warp filaments. This is achieved by a mechanical regulating device. The stress of the warp filaments is applied to control an infinitely variable transmission which, in turn, controls the speed of the warp beam depending on the stress of the warp filaments. The device according to the above referred-to Swiss Patent has, however, two serious drawbacks. First, it depends on mechanical regulating means which are subject to wear and tear, and second it does not allow a reversal of the sense of rotation, i.e. to take up rather than to unwind filaments.
Other relevant prior art are DE-AS Pat. No. 16 13 350 (Deutsche Auslegeschrift) and DE-OS Pat. No. 26 27 658 (Deutsche Offenlegungsschrift). The former describes the alternative operation of a coupling and of a break for regulating the drive of sewing machines. The latter describes a positioning drive including alternately operating couplings and breaks.
It is, therefore, the primary object of this invention to provide a device of the kind specified above which enables a continuous regulation of the number of revolutions per unit of time of the warp beam without resorting to mechanical means such as, for instance, levers.